1. Field of the Invention
This invention relates to a thermomagnetic recording apparatus, for example, facsimile receiver. More particularly, it relates to a novel thermomagnetic recording facsimile receiver in which information are recorded on a magnetic drum uniformly magnetized by the use of a thermal recording head, whereby a plurality of received pictures can be obtained at need.
2. Description of the Prior Art
At present, as recording systems in facsimile equipments of the simplified type or the spread type, there are thermosensitive recording, discharge breakdown recording, electrographic recording (of the type wherein an information is directly recorded on electrographic recording paper, and of the type wherein a latent image is once formed on an electrographic recording carrier and then developed, whereupon the developed image is transferred onto ordinary paper), electrophotography (of the type which employes electrophotosensitive paper, and of the type which transfers an image on a electrophotosensitive medium onto ordinary paper and which uses the electrophotosensitive medium repeatedly), etc. In these systems, the special kinds of paper are usually used for the recording, which incurs the disadvantage of high running cost. In the ordinary paper recording systems of the electrographic recording and the electrophotography, the apparent running costs are low owing to the ordinary paper recordings. Since, however, the lifetimes of the electrographic recording medium and the sensitive medium are comparatively short, it is present situation that when the expenses of consumption of the media are apportioned to the respective numbers of recorded pages, the running costs become approximately equal to those in the case of the recordings with the special kinds of paper.
It is well known that the discharge breakdown recording and the thermosensitive recording are inferior in points of the printing quality and the preservability of printed matter.
Although the electrographic recording or the electrophotography has no disadvantage as to the printing quality and the preservability, only one copy can be recorded for one received original. In the electrographic or electrophotographic recording of the transfer type, various systems for taking a plurality of copies from one latent image have been attempted, but there is the disadvantage that the second and further copies are conspicuously inferior in the picture quality to the first copy.
In the electrographic or electrophotographic recording, there is the trend that a one-component type magnetic developer (magnetic toner) of simple constituent is used for the development. In performing the electrographic recording or electrophotographic recording of the transfer type by the use of the magnetic toner, it becomes difficult to select the optimum resistance value of the magnetic toner. More specifically, in case where the resistance value of the magnetic toner is low, the development characteristic becomes good, but the transfer becomes difficult. Conversely, in case of a high-resistance magnetic toner, the transfer characteristic is improved, but the development density becomes low. It turns out that the optimum resistance region of the magnetic toner is not existent or is limited to a very narrow range, and there is the disadvantage that a stable operating characteristic cannot be attained.
As a recording system which has solved the various disadvantages mentioned above, there has been developed a magnetic recording system wherein a latent image is formed on a magnetic drum by the use of a magnetic head, it is developed with magnetic toner and the developed image is thereafter transferred onto ordinary paper. This system is freed from the narrow selectivity of the magnetic toner which has been the problem in the prior-art electrographic or electrophotographic recording system of the transfer type. That is, since the development is performed by sticking the magnetic toner by a magnetic attractive force, only the transfer characteristic may be noted as the electrical characteristic of the developer. Accordingly, the range of selection for the magnetic toner widens.
A disadvantage of the magnetic recording system is that the recording rate needs to be changed between the operation of forming the magnetic latent image and the subsequent operation of the development and the transfer. More specifically, the recording medium is usually constructed in the shape of a drum. It is extremely difficult and impossible in practice to construct the magnetic head in an elongate array shape. Therefore, a scanning system is adopted in which the rotary drum is scanned with a single head or a multi-head assembly including at most several heads. For this reason, the rotation of the magnetic drum in the operation of forming the magnetic latent image is set at a high rotational frequency, and once the magnetic latent image has been entirely formed on the drum, the number of revolutions of the drum is lowered, whereupon the respective stages of development, transfer, and fixation of the transfer are executed.
With such recording system, the rotation of the drum needs to be changed-over between the two sorts, and the running situation of the equipment during the formation of the latent image and that of the equipment during the development and transfer are conspicuously different, so that the equipment becomes complicated. This forms a hindrance to redering the size of the equipment small and the cost low.
As recording apparatuses wherein a magnetic latent image according to information is formed on a magnetic recording medium and wherein the magnetic latent image is developed with toner so as to obtain a visible image, there can be mentioned ones disclosed in U.S. Pat. No. 3,043,685 (Joseph F. Rosenthal), U.S. Pat. No. 3,512,170 (Alfred M. Nelson), U.S. Pat. No. 3,601,091 (George G. Preckshot), U.S. Pat. No. 3,816,799 (Owen J. Ott et al) and U.S. Pat. No. 3,832,718 (Ami E. Berkowitz et al).